ExcelCalcs Spreading Best Practise Across Industries

ExcelCalcs interdisciplinary approach to problems helps to deliver best practise from one industry to another. Two positive conclusions from two independent calculations is a very good way of building confidence in our designs. It provides a useful benchmark, opens your mind to other issues and considerations and is always useful for education and understanding. For example, a bridge engineer could check the design of a pinned joint using a code of practise from the aerospace industry. The aerospace industry were one of the first to address the problems of fatigue and had bridge designers been aware of this earlier perhaps the following bridge disasters could have been avoided.

The 41 year old Silver bridge across the Ohio river (533.4 m span) at Point Pleasant West Virginia collapsed in 1967. Silver bridge was a chain suspension structure that collapsed suddenly in rush-hour traffic on December 15, 1967, sending 75 vehicles into the water, killing 46 people and injuring hundreds of others. The cause? A pinned joint supporting a chain suffered a fatigue failure on the north side, toppling both towers and sending the bridge into the water. The fatigue failure was accelerated by the effects of corrosion and the joint was located in a place where it could not be inspected. A consequence of the failure was a new requirement that all bridges in USA should be inspected according to federal guidelines.

26 years later on June 28, 1983 the Mianus bridge near Greenwich, Connecticut collapsed and falling into the river.  Two tractor-trailers and two cars fell into the Mianus River.  There were three deaths and three serious injuries. The Mianus Bridge used simple spans which were supported at each corner by pin and hanger assemblies.  After the collapse, the missing hanger pin was found in the river below. It too suffered a fatigue failure exacerbated by corrosion and the state of Connecticut was faulted for inadequate inspections.

Understanding failures should lead to major progress but in the cases cited in this article we have seen that lessons are not always learned and history can repeat.

Sample Calculations for Pinned Joints

Aerospace_lug_analysis.xls

This method of assessment involves reading coefficients from graphical data for use in subsequent equations. The spreadsheet automates all the curve reading to determine the proof and ultimate strength of lugs in an expedient manner. The spreadsheet has been produced by Abbott Aerospace an independent consultancy company offering structural engineering services the aerospace industry.

API PADEYE Design

Design Check for padeyes per API (offshore/WSD-ASD)guide lines.

Clevis and lug design V0001.xls

Calculation of stress concentration effects at a pin and clevis joint. This calculation requires the XLC addin and the XlXtrFun to be installed. Calculation Reference - Peterson's Stress Concentration.

Pin and Lug.xls

Calculates the proof and ultimate strength of obliquely loaded lugs. Calculation References: Traditional UK railway method, A.P.T. Mechanical Design Note No APT/MD 257, Strength of Lugs in Fatigue by R. B Heywood, Stress, Strain and Strength by R. C. Juvinall.

Pin and Lug - Static and Fatigue.xls

Calculates the proof and ultimate strength of obliquely loaded lugs and the fatigue strength of lug. Calculation References: Traditional UK railway method, A.P.T. Mechanical Design Note No APT/MD 257, Strength of Lugs in Fatigue by R. B Heywood, Stress, Strain and Strength by R. C. Juvinall.

XLC Sample Design Calc Sheet - BTH pinned plate

This is an example of how to produce design calculations for a pinned connection using Excel with the XLC add-in. Design a Plate Lifting Beam and rigging plates to lift a 98 ft, 30" square PSC pile from the pile head using an embedded 2" ID PVC sleeve thru the pile width. The lifter will be capable of crane hook access and transfer the pile load from the lifting pin to the hook by means of independent eyebars from the pin to the plate spreader beam, shackles and a plate lifting beam connected to the hook.

Repository News

The ExcelCalcs repository continues to grow and we are delighted to receive calculations from you and we reward calculations with free XLC Pro subscriptions. Since the last newsletter ExcelCalcs user wnscott50 has posted a number of wood shear capacity calculations.

NDS Table A.4-2B Nominal Shear Capacity Unlblocked PLYWD Rev 0 wns03-02-10.xls

NDS Table A.4-2A Nominal Shear Capacity Rev 0 wns 030210.xls

NDS Table 4-2B Nominal Shear Capacity Rev 0 wns 030210.xls
NDS Table SDPWS Table 4.2A

Server Downtime

Apologies to all people trying to access ExcelCalcs on Friday 12th March and Saturday 13th March. The server suffered a power failure but the site was restored from a backup.

Recommended Reading

Jan Peczkis "Scholar and Thinker" (Chicago IL, USA) is a top 500 Amazon Reviewer. He says "Engineers and Engineering: Old engineering books often explain problems (with solved examples) better than new engineering works. Using old engineering books also allows for the engineer to have a more direct understanding of what is going on, in contrast to the "black box" approach when using FEM (finite-element analysis). Finally, old engineering books give the reader, engineer, and problem-solver a sense of the history of engineering. The first part of this list focuses on engineering books written not many years or decades ago. The rest of the list elaborates on engineering books going back 80 or more years, especially those I found helpful in explaining and solving engineering problems."

Related Consultancy Projects...

Pinned joints in Volvo loader arm.


Pinned joints in Claas Tele-handler.


Bruce's articulated head at Disneyland Paris.


Pinned articulated joint in wagon at Disneyland Paris.


Railway rod end investigation.


Pinned joints on the London Eye dummy pods.


Pinned hold down connection for Indiana Jones's bi-plane at Tokyo DisneySea.

Training Modules...

Select  your own course from the ExcelCalcs training modules.

• XLC and ExcelCalcs
  
• Bolting and mechanical fasteners
  
• Welding and joining materials
  
• Static strength and fatigue design
  
• Pins and lugs
  
• Failure criteria and biaxial stress assessment
  
• Material properties and material selection
  
• Steel and aluminium design
• Fatigue of welded structures
  
• Fracture mechanics
  
• Strain gauge or calculate?
  
• Failure Investigations
  
• Design for impact loads and dynamic effects